Material Selection8–10 min read
4140 vs 4340 Alloy Steel: Heat Treatment and Shaft Selection
Compare section size, toughness evidence and the final heat-treated condition.
Author: Mat Grades Editorial DeskRead Guide →
SAE 4140 Alloy Steel
Primary Designation:SAE 4140
Mat Grades internal verification confirms source-backed fidelity and data integrity. It does not constitute external certification or guaranteed lot conformity. Read engineering disclaimer →
Data Completeness:8 composition elements and 21 condition-specific property values cataloged.
Omitted fields represent unverified properties. "Missing is better than invented."
Key Engineering Properties
Representative source rows, qualified by their reported conditions. Inspect the tables below for all values, limits, and source notes.
Density
7.85 g/cm³TYPICAL · temperature not stated
Thermal Conductivity
42.6 W/(m·K)TYPICAL · at 100 °C
Composition Excerpt
C 0.38–0.43 wt%Carbon (range)
Standard Elemental Basis: RANGETensile Strength
930 – 1080 MPaRANGE · Quenched and tempered (voestalpine supply) · temperature not stated
Engineering Summary
SAE 4140 Alloy Steel. Source-scoped engineering data is shown with its reported limits and conditions. Unreported properties are not inferred.
Recognized Aliases
Source-backed commercial trade name and short designations cataloged in canonical data.
SAE 4140 Alloy Steel Specifications & Designations
Standard Designations & Applicable Specifications — Semantically classified designations distinguishing primary standard identifiers, commercial trade names, and applicable specification references.
Direct Standard DesignationsDIRECT DESIGNATION
2 Primary IdentifiersScroll horizontally for full designation data
| System | Identifier | Standard System Name | Classification Notes & Provenance |
|---|---|---|---|
| SAEPRIMARY | 4140 | SAE | —Ref: Practical Data for Metallurgists, 19th edition |
| AISI | 4140 | AISI | —Ref: AISI 4140 datasheet |
Applicable Specifications & Product Form ReferencesSPECIFICATION REFERENCE
1 Applicable StandardsScroll horizontally for full standard specifications
| Standards Body | Specification Code | Specification Title / Scope | Relationship Type |
|---|---|---|---|
| SAE | SAE 4140 Alloy Steel Engineering Datasheet | Applicable specification reference. | Specification Reference |
Engineering Notice: Applicable specifications establish manufacturing requirements, dimensional tolerances, and test criteria for specific product forms (e.g. bus bar, wire, plate, pipe). They represent applicable technical standards, not alternative or equivalent alloy grades.
SAE 4140 Alloy Steel Chemical Composition
Chemical Composition (Weight %) — Elemental limits and values from the cited source. Preserves exact semantic limits (minimums, maximums, and ranges).
Scroll horizontally for full elemental limits
| Element | Symbol | Atomic No. | Semantic Basis | Specified Value | Unit | Metallurgical Notes & Qualification | Data Status |
|---|---|---|---|---|---|---|---|
| Carbon | C | 6 | RANGE | 0.38 – 0.43 | wt% | Source cell: .38/.43. Scope: p6, SAE 4140.Ref: Metallus | VERIFIED |
| Manganese | Mn | 25 | RANGE | 0.75 – 1.00 | wt% | Source cell: .75/1.00. Scope: p6, SAE 4140.Ref: Metallus | VERIFIED |
| Chromium | Cr | 24 | RANGE | 0.80 – 1.10 | wt% | Source cell: .80/1.10. Scope: p6, SAE 4140.Ref: Metallus | VERIFIED |
| Molybdenum | Mo | 42 | RANGE | 0.15 – 0.25 | wt% | Source cell: .15/.25. Scope: p6, SAE 4140.Ref: Metallus | VERIFIED |
| Silicon | Si | 14 | RANGE | 0.15 – 0.35 | wt% | Source cell: .15/.35. Scope: p6, SAE 4140; p7 default footnote / row override.Ref: Metallus | VERIFIED |
| Phosphorus | P | 15 | MAXIMUM | ≤ 0.04 | wt% | Source cell: .035max. Scope: p6, SAE 4140; p7 default footnote / row override.Ref: Metallus | VERIFIED |
| Sulfur | S | 16 | MAXIMUM | ≤ 0.04 | wt% | Source cell: .040max. Scope: p6, SAE 4140; p7 default footnote / row override.Ref: Metallus | VERIFIED |
| Nickel | Ni | 28 | MAXIMUM | ≤ 0.25 | wt% | Source cell: .25max. Scope: p6, SAE 4140; p7 default footnote.Ref: Metallus | VERIFIED |
* Elemental percentages are expressed in weight percent (wt%). Values represent applicable specification limits. Unspecified trace elements are not fabricated or assumed.Preserves exact semantic basis
Property Display UnitsSwitch between Canonical SI and Source / US Customary units:
SAE 4140 Alloy Steel Physical Properties
Source-specific physical properties. Test temperatures are shown only where reported.
Scroll horizontally for full property parameters
| Property Parameter | Canonical SI Value | Semantic Basis | Test Temperature / Context Range | Source Raw Reference | Source Reference | Status |
|---|---|---|---|---|---|---|
| Density | 7.85 g/cm³ | TYPICAL | 7.85 g/cm3 | Ovako / Technical Steel Navigator | VERIFIED | |
| Elastic Modulus | 205 GPa | TYPICAL | 205 GPa | Ovako / Technical Steel Navigator | VERIFIED | |
| Poisson's Ratio | 0.29 dimensionless | TYPICAL | 0.29 dimensionless | Ovako / Technical Steel Navigator | VERIFIED |
SAE 4140 Alloy Steel Thermal & Thermodynamic Properties
Phase change temperatures, thermal conductivity, specific heat, mean coefficients of thermal expansion across standardized temperature ranges, and recommended thermal processing windows.
Scroll horizontally for full property parameters
| Property Parameter | Canonical SI Value | Semantic Basis | Test Temperature / Context Range | Source Raw Reference | Source Reference | Status |
|---|---|---|---|---|---|---|
| Coefficient of Thermal Expansion | 12.2 µm/(m·K) | TYPICAL | Test Temp: 100 °C | 12.2 10^-6/K | Ovako / Technical Steel Navigator | VERIFIED |
| Thermal Conductivity | 42.6 W/(m·K) | TYPICAL | Test Temp: 100 °C | 42.6 W/(m·K) | Ovako / Technical Steel Navigator | VERIFIED |
SAE 4140 Alloy Steel Mechanical Properties
Contextual Mechanical Properties & Tempers: Engineering strength, ductility, and hardness values grouped by product form, temper, and section thickness. Mechanical properties are contextual and not isotropic averages.
Showing 10 of 10 conditions
Scroll horizontally for all conditions & tempers
| Product Form | Temper / Condition | Section Size | Tensile (UTS) | Yield Strength | Elongation | Shear Strength | Fatigue Strength | Hardness (Scales Preserved) | Status |
|---|---|---|---|---|---|---|---|---|---|
| Bar | Quenched and tempered (voestalpine supply) · Quenched and temperedSource values and qualifiersTensile Strength: 930–1080 MPa (RANGE)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition Yield Strength: ≥ 740 MPa (MINIMUM)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition Elongation: ≥ 12 % (MINIMUM)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments. Gauge length A5.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition HB Hardness: 269–331 HB (RANGE)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition | — · 10–100 mm | 930–1080 MPa | ≥ 740 MPa | ≥ 12 % | — | — | 269–331 HB | VERIFIED |
| Bar | Quenched and tempered (voestalpine supply) · Quenched and temperedSource values and qualifiersTensile Strength: 850–1000 MPa (RANGE)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition Yield Strength: ≥ 665 MPa (MINIMUM)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition Elongation: ≥ 13 % (MINIMUM)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments. Gauge length A5.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition HB Hardness: 248–302 HB (RANGE)voestalpine supply properties for the stated section range; source does not specify test temperature. Not extrapolated to other products or heat treatments.voestalpine High Performance Metals Australia — p1 mechanical table; p2 supply condition | — · 101–250 mm | 850–1000 MPa | ≥ 665 MPa | ≥ 13 % | — | — | 248–302 HB | VERIFIED |
| Bar | Annealed Bar · Annealed 840°C furnace cooledSource values and qualifiersUltimate Tensile Strength: ≥ 655 MPa (MINIMUM)ASTM A29Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Soft Annealed Condition Table | — | ≥ 655 MPa | — | — | — | — | — | VERIFIED |
| Bar | Annealed Bar · Annealed 840°C furnace cooledSource values and qualifiersYield Strength: ≥ 415 MPa (MINIMUM)ASTM A29 (0.2% offset)Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Soft Annealed Condition Table | — | — | ≥ 415 MPa | — | — | — | — | VERIFIED |
| Bar | Annealed Bar · Annealed 840°C furnace cooledSource values and qualifiersElongation at Break: ≥ 20 % (MINIMUM)ASTM A29Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Soft Annealed Condition Table | — · in 50 mm (2 in) | — | — | ≥ 20 % | — | — | — | VERIFIED |
| Bar | Normalized Bar · Normalized 870°C air cooledSource values and qualifiersUltimate Tensile Strength: ≥ 930 MPa (MINIMUM)ASTM A29Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Normalized Condition Table | — | ≥ 930 MPa | — | — | — | — | — | VERIFIED |
| Bar | Normalized Bar · Normalized 870°C air cooledSource values and qualifiersYield Strength: ≥ 600 MPa (MINIMUM)ASTM A29 (0.2% offset)Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Normalized Condition Table | — | — | ≥ 600 MPa | — | — | — | — | VERIFIED |
| Bar | Normalized Bar · Normalized 870°C air cooledSource values and qualifiersElongation at Break: ≥ 15 % (MINIMUM)ASTM A29Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Normalized Condition Table | — · in 50 mm (2 in) | — | — | ≥ 15 % | — | — | — | VERIFIED |
| Bar | Annealed BarSource values and qualifiersHB Hardness: ≤ 229 HB (MAXIMUM)Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Soft Annealed Condition Table | — | — | — | — | — | — | ≤ 229 HB | VERIFIED |
| Bar | Normalized BarSource values and qualifiersHB Hardness: ≥ 269 HB (MINIMUM)Ovako / Technical Steel Navigator — Ovako 4140 Technical Bulletin, Normalized Condition Table | — | — | — | — | — | — | ≥ 269 HB | VERIFIED |
Hardness Integrity Notice: Rockwell B (HRB), Rockwell F (HRF), and Superficial 30T (HR30T) scales are reported on their measured scales without cross-scale mathematical conversion.
Source: See fact-level citations
Practical Engineering & Fabrication Notes
By Mat Grades Editorial Desk · Updated 2026-11-14. Use alongside the specified product standard and supplier certificate.
Machining & shop-floor behavior
For SAE 4140 Alloy Steel, a qualified cutting-speed or tool-life recommendation is not supplied in the available record. A relevant hardness example is HB Hardness: 269–331 HB (range; Quenched and tempered (voestalpine supply), Bar). Use that supplied condition for a trial of the difficult feature. Record tool changes, burr removal, unclamped dimensions and accepted parts per hour. Relative machinability ratings from different reference scales should not be compared as if they were one common test.
Weldability, brazing & joining
No qualified weld procedure, filler selection or preheat/interpass schedule is established by this material record. Obtain a procedure for the actual joint, supplied condition and section rather than copying one from a nearby grade. The first cataloged strength example is Tensile Strength: 930–1080 MPa (range; Quenched and tempered (voestalpine supply), Bar). Assess the final part after joining or thermal processing. Include distortion, cleanup and inspection in the quotation. A material designation or favorable process rating is a starting point for qualification, not evidence that an untested joint meets the drawing.
Corrosion & service environment
Plan corrosion protection and inspect how the finish affects threads, bearing fits and repaired surfaces. A steel strength value does not establish corrosion life. Where cyclic load or impact matters, retain the surface condition and the required toughness evidence with the material decision. The recorded thermal example is Coefficient of Thermal Expansion: 12.2 µm/(m·K) (typical; ; test temperature 100 °C). State the exposure and inspection access in the design record so that a change of installation or cleaning method triggers a review. The selected composition entries are C 0.38–0.43 wt%, Mn 0.75–1 wt%, Cr 0.8–1.1 wt%. Chemistry documents identity; it does not establish fluid compatibility.
Selection trade-offs & applications
For a shaft, specify the ruling section and final quenched-and-tempered condition. Compare through-section properties and toughness evidence with 1045 or 4340, rather than assigning a small test-bar result to the center of a larger component. The listed forms include Bar; confirm the actual stock offered by the supplier. Compare the complete route through machining, joining, finish and inspection. Keep the certificate, required test location and acceptance criteria with the first-article record. A later change of grade, condition or source should be assessed against that same requirement.
Technical references: Ovako / Technical Steel Navigator; voestalpine High Performance Metals Australia; Metallus
Chromium-Molybdenum Alloy Steel Cluster (41xx Series)
High-strength Cr-Mo alloys providing deep hardenability, high fatigue strength, and impact toughness across elevated stress applications.
4140Current Grade
SAE 4140 Alloy Steel
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Sources
Sources & Provenance Trail: Authoritative reference publications, standards specifications, and data registers cited across this material record.
MetallusPractical Data for Metallurgists, 19th edition
PRIMARY PRODUCER
Reviewed factual transcription; source document SHA-256 is recorded in the capture metadata. No cross-standard equivalence is asserted.
MetallusPractical Data for Metallurgists, 19th edition
PRIMARY PRODUCER
Reviewed factual transcription; source document SHA-256 is recorded in the capture metadata. No cross-standard equivalence is asserted.
MetallusPractical Data for Metallurgists, 19th edition
PRIMARY PRODUCER
Reviewed factual transcription; source document SHA-256 is recorded in the capture metadata. No cross-standard equivalence is asserted.
Ovako / Technical Steel NavigatorOvako Steel Navigator & Technical Engineering Specifications
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Ovako / Technical Steel NavigatorRevision: Steel Navigator Revision 2024View Source Record ↗
Ovako / Technical Steel NavigatorOvako Steel Navigator & Technical Engineering Specifications
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Ovako / Technical Steel NavigatorRevision: Steel Navigator Revision 2024View Source Record ↗
Ovako / Technical Steel NavigatorOvako Steel Navigator & Technical Engineering Specifications
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Ovako / Technical Steel NavigatorRevision: Steel Navigator Revision 2024View Source Record ↗
voestalpine High Performance Metals AustraliaAISI 4140 datasheet
PRIMARY PRODUCER
Reviewed factual transcription; source document SHA-256 is recorded in the capture metadata. No cross-standard equivalence is asserted.
Ovako / Technical Steel NavigatorOvako Steel Navigator & Technical Engineering Specifications
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Ovako / Technical Steel NavigatorRevision: Steel Navigator Revision 2024View Source Record ↗
Ovako / Technical Steel NavigatorOvako Steel Navigator & Technical Engineering Specifications
PRIMARY PRODUCER
Reviewed factual transcription from primary producer engineering datasheet.
Issuing Body: Ovako / Technical Steel NavigatorRevision: Steel Navigator Revision 2024View Source Record ↗
voestalpine High Performance Metals AustraliaAISI 4140 datasheet
PRIMARY PRODUCER
Reviewed factual transcription; source document SHA-256 is recorded in the capture metadata. No cross-standard equivalence is asserted.
Intellectual Property & Provenance Notice: Mat Grades cites technical literature from recognized industry associations and standards organizations. Underlying technical standards and publication data remain the intellectual property of their respective issuing organizations.